I'm currently on Androcur only, the current best practise here in Canada is 5-6 weeks of blockers and then add estrogen, the theory is to make sure your body copes with the anti-androgen they prescribe, if you have an adverse reaction they can switch you to a different anti-androgen without having to worry if your bad reaction was to the estrogen or the anti-androgen, change one variable at a time, give it time to balance out and then change the next variable.
As far as the cramps go, I assume you are on Spiro, if this is a correct assumption keep in mind that it's primary use is as a diuretic, it makes your kidneys flush out water from your body which means you have to be careful to keep hydrated, watch your potassium levels (from going too high, salt substitutes, bananas, etc), this is especially true when exercising.
The physical changes will be minimal, think pre puberty, you will notice some male specific things go away such as libido, the smell of your sweat/urine will change, hair loss will stop and your skin will soften.